/**
 * Copyright (c) 2017-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @flow
 * @format
 */

import invariant from 'assert';

export function getUsername(): string {
  // It is slightly more robust to get the uid and look it up in /etc/whateveritis.
  const {env} = process;
  const username = env.LOGNAME || env.USER || env.LNAME || env.USERNAME;
  invariant(username);
  return username;
}
